The oldest active US 74-A was born in 1994 as a replacement for mainline US 74 and is the 9th US 74-A. It begins at I-40/US 74 at the US 19-23 Enka exit and follows US 19-23 to Asheville, then I-240/US 70, Charlotte St and Tunnel Rd southeast to Fairview, Bat Cave, Chimney Rock, Lake Lure, Rutherfordton before ending at the relocated US 74 south of Forest City.
US 74-A hasn't had any changes and follows much of original NC 20.

US 74 through Lake Lure and Chimney Rock
1993-94 Official

US 74 through Lake Lure and Chimney Rock
1999 Official

The newest active US 74-A was created in Oct 2007 (NCDOT) when US 74 was placed on newly constructed I-74 from the Maxton Bypass to just east of I-95.
The 2008 Official map erroneously labels this as US 74 Business.
US 74-A does not have an interchange with I-95 as the original Exit 14 with US 74 was removed.

US 74 east of Maxton
2008 Official

US 74-A arrives
2011 Official

Now a chronological look at decommissioned US 74-A routes:

The 1st US 74-A appeared around 1936. It ran through the actual village of Leland on Thomas Ave while mainline US 74 used Village Rd. This routing is shown as unlabeled primary route on County maps from 1936-63 and labeled explicitly on county maps 1967 and onward.
This US 74-A was decommissioned in Sept 1975 (NCDOT) when US 74-76 was moved from Village Rd to its current expressway. Today it appears the west end of this US 74-A no longer connects to Village Rd.

unlabeled US 74-A in Leland
1936 Brunswick County

Labeled US 74-A in Leland
1967 Brunswick County

US 74-A in Leland decommissioned
1980 Brunswick County

Just in case you might be thinking that was a mapo or copyright trap, here is a screen shot of the NCDOT document decommissioning US 74-A in Leland:

US 74-A sent to retirement by NCDOT.
Sept 1975 NCDOT Route Change Document

The 2nd US 74-A was also created about 1936 as a new primary route using Marion St through Shelby. Shown but unlabeled on the 1936 Cleveland County map but labeled on 1938 maps and later.
About 1949, US 74-A was extended out in both directions to replace mainline US 74 which had been placed on its current bypass. As part of this development, Marion St became US 74-A west and Warren St became US 74-A east.
In 1960, US 74-A was renumbered as US 74 Business. Today Warren St is no longer primary east of DeKalb St.

US 74-A appears in Shelby
1938 Cleveland County

US 74-A expanded through Shelby
1949 Cleveland County

US 74-A becomes US 74 Business
1968 Cleveland County

The 3rd US 74-A was born in 1937 when US 29-74 was rerouted to run from Kings Mountain to Gastonia without going to Bessemer City.
US 74-A was short lived and was renumbered as parts of NC 161 and NC 274 in 1938.

US 29-74 through Bessemer City
1932 Texaco

US 29A-74A through Bessemer City
1938 Gen Draft

NC 161 replaces US 74-A
1938 Official

The 4th US 74-A appeared in 1937 or 1938 as new primary routing in Wrightsville Beach, running along Waynick Blvd south of Causeway Dr.
About 1940, US 74-A was renumbered as part of US 76.

US 74-A at Wrightsville Beach
1938 New Hanover County

US 74-A replaced by US 76
1944 New Hanover County

The 5th US 74-A was created between 1945-49 as an inner bypass of downtown Monroe, using Jefferson St (mainline US 74 was using Charlotte Ave/Franklin St.
About 1952, US 74-A was decommissioned when the current US 74 bypass was built and Charlotte Ave/Franklin St became its own US 74-A.

US 74-A downtown Monroe
1949 Union County

The 6th US 74-A was created in 1948 or 1949 when US 74 was given its first bypass of Rutherfordton via Ruth.
In 1960, US 74-A was renumbered as US 74 Business.

US 74 through Rutherfordton
1944 Rutherford County

US 74-A through Rutherfordton
1949 Rutherford County

US 74-A becomes US 74 Business
1962 Rutherford County

THe 7th US 74-A was created between 1950-53, when US 74 was placed on today's US 74 Business in Rockingham. The old route using Washington/Rockingham Sts. became US 74-A.
US 74-A was decommissioned by 1957.

US 74 through central Rockingham
1949 Richmond County

US 74-A through central Rockingham
1953 Richmond County

The 8th US 74-A was created about 1952 when US 74 was given its bypass of Monroe.
It appears US 74-A was decommissioned by 1954.